ANT 326 Human Osteology

Tuesday, September 11, 2012

Finishing up on Appendicular Skeleton I:  Humerus, Radius, Ulna

Radius:  Here is a description of the 8 features listed on your handout/notes from class.  The image below has some of these features labeled.  Please refer to Bass and White et al. and come to the lab to see the bones and familiarize yourself with the location of these features.

1. Head:  Located proximally, it's the round portion that rotates along the capitulum of the humerus so that the hand can turn from palm-up to palm-down.
    
2. Neck:  The tapered portion inferior to the head, yet still on the proximal portion of the bone.
    
3. Radial tuberoisty:  The bump inferior to the neck.  It's for muscle attachment.
    
4. Nutrient foramen:  Hole or opening for a major blood vessel.  Its placement varies along the diaphysis of the bone.
    
5. Interosseous crest:  The sharp ridge of bone running along the diaphysis ("inter" = between, "osseous" = bone; it's the sharp region where muscles attach between the radius and the ulna).  It's not pictured below, but you can see it in Bass and White et al.
    
6. Styloid process:  This is a tiny point, distally.  Think "stylus" as in "pen" and a pen-point.  More than one bone has a styloid process (e.g., ulna, pictured below).
    
7. Dorsal tubercles:  Little bumps on the dorsal (back) side of the radius, distally.  Please see Bass and White et al. 
    
8. Ulnar notch:  This is an indentation on the lateral side of the distal portion of the radius; it is named the "ulnar" notch because it is a facet for articulation with the head of the ulna.

• Oftentimes, features involved in articulations (bone connections) have names that relate to what is articulating with them.  Thus, the radius has a feature--the ulnar notch--so named because that's where the head of the ulna articulates.
   
• Features that are for muscle attachment (not connections with other bones) may have names that refer to the bone itself, such as the radial tuberosity on the radius, which is bump for muscle attachment.
   

Image from:  http://www.cas.muohio.edu/~meicenrd/mudescd/Bot630DProjects/2003Botany630WProjects/Bones/RADIUS&ULNA.JPG

• Please note the plural for radius is radii (ray-dee-eye); and the plural for humerus is humeri (hyoo-mur-eye).

Ulna:  Here I will cover the 8 features listed on your handout; you can refer to the photo above and please also use your White textbook and Bass field guide.  Remember to come to the lab to practice "siding" bones and locating features ("siding" = determining if a paired bone is a left or right).  The plural of ulna is ulnae (ul-nye in proper Latin pronounciation; but, you'll often hear it pronounced "uhl-nee"). 

1. Olecranon:  This is the feature superior on the proximal portion of the bone; it's the part of the bone that makes that bump we call the elbow.
    
2. Semilunar notch:  This is the half-moon ("semi" means half and "lunar" means moon) shaped indentation; it's where the ulna articulates with the trochlea of the humerus.  Note that in the photograph above it's called the "trochlear notch".  We are learning the "semilunar notch" variation.  Recall that many terms are synonymous; however, to keep things simpler, please use the preferred term from class.
    
3. Coronoid process:  This is a sharp projection of bone anteriorly located on the proximal portion of the bone. Please pay careful attention to the "n" in "coronoid" and link it to the "n" in "ulna" because soon we'll learn other features of other bones that have very similar sounding names (i.e., coracoid process, conoid process, etc.).
    
4. Radial notch:  This is the indentation just lateral to the coronoid process on the proximal portion of the bone.  Similar to the ulnar notch of the radius, the radial notch of the ulna is named for the bone/feature that articulates with it. Thus, the radial notch is for the head of the ulna.  Note in the photograph above that the head of the ulna is distal.  We must think of "heads" of bones as features named for the shape:  roundish, as opposed to location (i.e., the head is not always superior or proximal or at the top; it's a "head" because it's "head" or "round" shaped).
    
5. Nutrient foramen:   Similar to the radius, this is the opening for the blood vessel and it's oriented such that it's toward the elbow.  Therefore, the opening in the bone where the blood vessel enters is inferior (it's also inferior on the radius; but recall from class that it's superior in the humerus).  Also, please note that the nutrient foramen is not seen/labeled in the above photograph.  You have to be fairly close to the bone to see it well as it's tiny.
    
6. Interosseous crest:  Similar to the feature of the same name on the radius, this is the long sharp ridge of bone traveling along the lateral side of the diaphysis (shaft).  Muscles involved in pronation and supination (turning the hand palmar and dorsal) attach along these crests of the ulna and radius.  This featuer is not labeled in the above photograph; however, your White text and Bass field guide will show it.
    
7. Styloid process:  Located on the head of the ulna (distal), this is the projecting point lateral near your wrist. Remember, just like the styloid process of the radius, the styloid process of the ulna is like a pen-tip (think of "le stylo" or pen in French).
    
8. Head:  Round part of the bone.  The head of the ulna is unusual in that it is distally located.